Desert Heat and My Poor Roadster

At about 12:30 pm this afternoon in Phoenix the ambient temp was 108 F. My Roadster just ran a COOLDOWN cycle.

Check out what the ambient temperature on the car is reading. Yikes! I don't have a garage at home and am in the process of having a carport designed, so my car currently sits outside plugged in under a car cover.

Why so much air in the tires? I run 30/40 and Tesla tells me that is the high end.

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Since most air pressure recommendations assume something like cool tires (eg, 68 or something like that), could it be they were filled at a lower temp and now at the higher temp just have higher pressure?

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Wow, your car is even starting to glow yellow/orange in the heat! :wink:

Since most air pressure recommendations assume something like cool tires (eg, 68 or something like that), could it be they were filled at a lower temp and now at the higher temp just have higher pressure?

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Exactly. 2 days before that pic, the car was in for annual service. I imagine in the nicely AC-cooled service center, they reset the tire pressures to factory settings and the pressures increased with the heat.

With ambient temperatures above 115F yesterday (I think 117F peak); my car goes into "reduced power" mode on days like that if I punch it too much...

I just did a PEM cleaning a couple days ago because it got to the point it shut me down and I had to get towed home, no shut-downs since...

Cleaning the PEM is relatively easy with the right tools, there are about 8 wires and 8 bolts and 4 wiring harnesses that need to be removed then you lift it out and blow the heat-sinks out... Us Phoenix drivers should probably do this more often than just annually!

I set up a portable A/C unit to cool my battery in my car while it was in the garage. I only suffer from Texas heat and not Arizona heat, but the top of the battery case got down to around 70 degrees over night; the coolant reservoir felt cool to the touch. I went out and drove it when it was in the low 90's outside. I drove for about 20 minutes (some of it aggressively), and the battery temperature didn't increase from the second lowest bar. The thing that was really nice about having a chilled battery was that the motor and the PEM cooled down when I was stopped at lights; I don't recall seeing this before. I wish there were a hot weather mode in the Roadster where it would chill the battery as much as it could (even when the car isn't plugged in). I'm sure you could get a lot of spirited driving in when it's 40C if the battery coolant started out at 0C.

I set up a portable A/C unit to cool my battery in my car while it was in the garage.

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So, I've been wondering about this... When the circulating pump is running, the coolant must still be going through the evaporator / radiator setup at the front of the car, where the A/C air would flow during cool-down, right? But, without the A/C actually running, the two front fans aren't spinning, so that whole setup is really not doing any good.

When the car is sitting there, pump running but otherwise off, wouldn't an external fan blowing at the front of the car help the battery cool down to ambient more quickly? Or, is there a baffle in the way that would prevent it?

So, I've been wondering about this... When the circulating pump is running, the coolant must still be going through the evaporator / radiator setup at the front of the car.

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Nope there is an AC/antifreeze exchanger next to the ESS, the circulating antifreeze coolant basically stays near/in the ESS. It's likely reason to keep running is to keep cells temps even for better cell life.

At about 12:30 pm this afternoon in Phoenix the ambient temp was 108 F. My Roadster just ran a COOLDOWN cycle.

Check out what the ambient temperature on the car is reading. Yikes! I don't have a garage at home and am in the process of having a carport designed, so my car currently sits outside plugged in under a car cover.

It's a tough time of year.

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May be a dumb question, but where is that overhead screenshot with temperatures and PSI readings from?

May be a dumb question, but where is that overhead screenshot with temperatures and PSI readings from?

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I see you are in the Bay Area. If you would like to see the OVMS hardware installed in one, you are welcome to come see my Roadster. I'm away until the end of the month but PM me and we can arrange a meeting in September.
The OVMS is a wonderful addition to a Roadster, thanks to Mark for all his hard work making it happen!

Cleaning the PEM is relatively easy with the right tools, there are about 8 wires and 8 bolts and 4 wiring harnesses that need to be removed then you lift it out and blow the heat-sinks out... Us Phoenix drivers should probably do this more often than just annually!

Yes thanks to Mark but don't forget to thank Scott Swazey who developed the first Roadster monitoring system and made it possible for Mark to work on OVMS. Scott was the first, AFIK, to tap into the CAN bus and start decoding the messages with some assistance from others. He then very generously shared his knowledge with Mark, who generously gave a lot of his time to this community and continues to do so.

May be a dumb question, but where is that overhead screenshot with temperatures and PSI readings from?

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The links others included are for you to learn about the device.

In a nutshell, there is a relatively cheap device that plugs into the OBD port of the Roadster and several other EV's.

The picture you asked about is a screenshot of the iOS/Android App screen that provides real-time monitoring of the car, as well as allows remote lock and unlock and GPS/LOJAK style location capability, data logging, etc...

The device requires a SIM card, is easily affordable, and is well described on several threads and BB's on this forum.